A driver circuit for a brushless DC motor having a stator embodied as a quadruple T armature and having a radially outward-lying rotor with six permanent magnetic poles is known from U.S. Pat. No. 4,710,684.
A brushless single-phase DC motor is known from U.S. Pat. No. 4,737,674. In FIG. 2 of that publication there is a brushless DC motor having a stator embodied as a quadruple T armature and having an outward-lying rotor with four permanent magnetic poles for one direction of rotation only. The T armatures are configured asymmetrically and form an air gap increasing in the circumferential direction with respect to the oppositely disposed rotor to allow self-starting of the motor. Compared to the stator, the rotor is positioned radially outwardly. Furthermore, the rotor is connected to a spring device by means of which a restoring force is applied to the rotor in the event that the latter is deflected from a rest position. The motor control unit has electrically actuated switching means for the DC motor for applying a torque having a predefinable direction of rotation. It is furthermore configured to connect the armature coils to the voltage supply unit by way of the switching means in accordance with the predefined direction of rotation and as a function of a rotational position of the rotor. The rotor of the DC motor is connected to a spring device by means of which a restoring force is applied to the rotor in the event that the latter is deflected from a rest position.
DC motors require a commutation of the phases to take place during operation. The activation of the phases of the DC motor is therefore dependent among other things on the rotational position of a rotor of the DC motor. The commutation causes the phases of the DC motor to be energized with the correct current. The commutation may be realized by means of components known as commutation brushes. Such an embodiment is subject to wear and tear, however. For this reason the commutation is generally performed electronically in the prior art. The rotational position of the rotor may be determined or detected, e.g., by means of devices known as Hall-effect sensors. This principle is described, for example, in the US patent application 2005/0001570 A1.
Further actuators which permit the rotational position of the rotor to be determined without sensors are known from the international publications WO 2005/119898 A2 and WO 2013/045186 A2.